Calibration devices based on conventional art are well known to be used for calibration for deriving attitude parameters of a camera mounted to an automobile (see PLT1).
The calibration device described in PLT 1 performs bird's eye view conversion for a given calibration target shown in a captured image. This calibration device searches and identifies a roll (rotation about the longitudinal axis), a pitch (rotation about the lateral axis), and a vertical position of the camera, which bring about conversion results that are most approximate to the shape and size of the actual target. The given calibration target herein refers to an object to be imaged having a given shape and size and disposed at a predetermined position.
The calibration device acquires a vehicle speed and a rotation angle from a vehicle speed sensor for detecting a speed of the own vehicle, and a rotation angle sensor for detecting a rotation angle of the own vehicle about an axis perpendicular to the horizontal plane. The calibration device uses the acquired vehicle speed and rotation angle as a basis to search and identify an x-coordinate, a y-coordinate, and a yaw (rotation about a vertical axis), which minimize the positional difference and the rotational difference of a fixed object shown in images captured at different points.